Luminescence concentrators are known in the art. U.S. Pat. No. 7,982,229, for instance, describes amongst others a light emitting device comprising at least one LED which emits light in the wavelength range of ≥220 nm to ≤550 nm and at least one conversion structure placed towards the at least one LED without optical contact, which converts at least partly the light from the at least one LED to light in the wavelength range of ≥300 nm to ≤1000 nm, characterized in that the at least one conversion structure has a refractive index n of ≥1.5 and ≤3 and the ratio A:E is ≥2:1 and ≤50000:1, where A and E are defined as follows: the at least one conversion structure comprises at least one entrance surface, where light emitted by the at least one LED can enter the conversion structure and at least one exit surface, where light can exit the at least one conversion structure, each of the at least one entrance surfaces having an entrance surface area, the entrance surface area(s) being numbered A1 . . . An and each of the at least one exit surface(s) having an exit surface area, the exit surface area(s) being numbered E1 . . . En and the sum of each of the at least one entrance surface(s) area(s) A being A=A1+A2 . . . +An and the sum of each of the at least one exit surface(s) area(s) E being E=E1+E2 . . . +En.
US2011/0025951 describes a spectral conversion device including a plurality of discrete units dyed with a photoluminescent material at a concentration greater than or equal to an amount sufficient to absorb and convert substantially all input light from a light source to a desired output spectrum, and a coating material disposed around the discrete units, wherein the coating material binds the plurality of discrete units to form a matrix, wherein when the plurality of discrete units are positioned over the light source, the input light passing through the transparent discrete units is not converted, and the input light passing through the doped discrete units is converted to red and green wavelengths, further wherein the emitted input light and the converted red and green light correspond to the desired output spectrum to produce one or more colors. An associated method and an associated device used with flat panel image displays are also provided.